Like the American H-bomb testing, the Fukushima nuclear accident deposited Cs-137 over 600,000 square-miles of the Pacific, as well as the Northern Hemisphere and Europe. With a half-life of 30 years, Cs-137 taken up in the meat of the tuna, as if it were potassium, indicating that the metabolism holds on to it. According to a previously secret 1955 memo from the U.S. Atomic Energy Commission regarding concerns of the British government over contaminated tuna, "dissipation of radioactive fall-out in ocean waters is not a gradual spreading out of the activity from the region with the highest concentration to uncontaminated regions, but that in all probability the process results in scattered pockets and streams of higher radioactive materials in the Pacific. We can speculate that tuna which now show radioactivity from ingested materials have been living, in or have passed through, such pockets; or have been feeding on plant and animal life which has been exposed in those areas."